<template>
  <transition name="collapse-transition" v-on="on">
    <slot />
  </transition>
</template>
<script lang="ts" setup>
  import type { RendererElement } from '@vue/runtime-core';

  const on = {
    beforeEnter(el: RendererElement) {
      if (!el.dataset) el.dataset = {};

      el.dataset.oldPaddingTop = el.style.paddingTop;
      el.dataset.oldPaddingBottom = el.style.paddingBottom;

      el.style.maxHeight = 0;
      el.style.paddingTop = 0;
      el.style.paddingBottom = 0;
    },

    enter(el: RendererElement) {
      el.dataset.oldOverflow = el.style.overflow;
      if (el.scrollHeight !== 0) {
        el.style.maxHeight = `${el.scrollHeight}px`;
        el.style.paddingTop = el.dataset.oldPaddingTop;
        el.style.paddingBottom = el.dataset.oldPaddingBottom;
      } else {
        el.style.maxHeight = 0;
        el.style.paddingTop = el.dataset.oldPaddingTop;
        el.style.paddingBottom = el.dataset.oldPaddingBottom;
      }

      el.style.overflow = 'hidden';
    },

    afterEnter(el: RendererElement) {
      el.style.maxHeight = '';
      el.style.overflow = el.dataset.oldOverflow;
    },

    beforeLeave(el: RendererElement) {
      if (!el.dataset) el.dataset = {};
      el.dataset.oldPaddingTop = el.style.paddingTop;
      el.dataset.oldPaddingBottom = el.style.paddingBottom;
      el.dataset.oldOverflow = el.style.overflow;

      el.style.maxHeight = `${el.scrollHeight}px`;
      el.style.overflow = 'hidden';
    },

    leave(el: RendererElement) {
      if (el.scrollHeight !== 0) {
        el.style.maxHeight = 0;
        el.style.paddingTop = 0;
        el.style.paddingBottom = 0;
      }
    },

    afterLeave(el: RendererElement) {
      el.style.maxHeight = '';
      el.style.overflow = el.dataset.oldOverflow;
      el.style.paddingTop = el.dataset.oldPaddingTop;
      el.style.paddingBottom = el.dataset.oldPaddingBottom;
    },
  };
</script>

<style lang="scss">
  .collapse-transition-enter-active,
  .collapse-transition-leave-active {
    transition: height 0.3s ease-in-out, padding 0.3s ease-in-out, max-height 0.3s ease-in-out;
  }
</style>
